Same-sex marriage is legal in nine states and the District of Columbia. The states are Connecticut, Iowa, Maine, Maryland, Massachusetts, New Hampshire, New York, Vermont and Washington. It was legal in California for less than five months in 2008.
The justices chose for their review the case of Edith Windsor, 83, of New York, who sued to challenge a $363,000 federal estate tax bill after her partner of 44 years died in 2009.
Windsor, who goes by Edie, married Thea Spyer in 2007 in Canada after doctors told them that Spyer would not live much longer. She suffered from multiple sclerosis for many years. Spyer left everything she had to Windsor.
There is no dispute that if Windsor had been married to a man, her estate tax bill would have been zero.
The U.S. 2nd Circuit Court of Appeals in New York agreed with a district judge that the provision of DOMA deprived Windsor of the constitutional guarantee of equal protection of the law.
Like the Proposition 8 case from California, Windsor's lawsuit could falter on a legal technicality without a definitive ruling from the high court.
The House Republicans, the Obama administration and a lawyer appointed by the court especially to argue the issue spent the first 50 minutes Wednesday discussing whether the House Republican leadership can defend the law in court because the administration decided not to, and whether the administration forfeited its right to participate in the case because it changed its position and now argues that the provision is unconstitutional.
If the Supreme Court finds that it does not have the authority to hear the case, Windsor probably would still get her refund because she won in the lower courts. But there would be no definitive decision about the law from the nation's highest court, and it would remain on the books.